Calling device



' H. E. ELRQD I CALLING DEVICE Filed April 8. 1921 Patented Dec. 2, 1924.

unirao stares HENRY E. ELROD, F DALLAS, TEXAS.

CALLING DEVICE.

Application filed April 8, 1821.

To all whom it may concern:

Be it known that I, HENRY E. EL-ROD, a citizen of the United States, and a resident of Dallas, and county of Dallas and State of Texas, have invented certain new and useful Improvements in Calling Devices, of which the following is a specification.

My invention relates to calling devices and more particularly to devices known as impulse senders, employed in automatic and semi-automatic telephone systems for the purpose of controlling the operation of associated switching mechanisms.

Devices of'this type are used to enable the calling subscriber to transmit a definite identifying series of impulses. The arrangement of the parts are such that the device may be operated in a simple manner for transmitting these impulses and with the parts, will under all circumstances return automatically to their normal position.

The particular object of this invention is to provide a device of this type which is simple in construction and in which the possibility of erroneously operating the device and consequently damaging the parts is reduced to a minimum.

The parts comprising the mechanism are so shaped that most of them can be made of stamped material therefore eliminating to a great extent the necessity of machine tool work. Consequently the cost of constructing these devices is reduced to a minimum.

The various features and operation of my improved device will be made more apparent in the accompanying specification and drawings in which:

Fig. 1 is a top plan view of the device,

Fig. 2 is an enlarged vertical section,

Fig. 3 is a rear elevation,

Fig. 4 is a similar view with certain parts omitted,

Fig. 5 is a detailed elevation of certain parts,

Fig. 6 is a perspective view of a clutch disc,

Fig. 7 is a detailed perspective view of part of the device, and

Fig. 8 is a detailed view of a modified form of the escapement mechanism employed.

I will refer now more particularly to the drawings wherein the numeral 10 represents a circular metal main or base plate apertured at its center to receive a metal journal or hearing sleeve 11 formed preferably of brass Serial No. 459,626.

and pressed into the aperture formed centrally of the main plate 10. Rotatably sup ported within the journal 11 is a shaft 12 formed preferably of steel. The shaft 12 carries on its front end a finger plate 13 rigidly secured to the shaft 12 by a suitable bolt 14. The finger plate 13 is provided with multiplicity of radially disposed apertures 15 for a purpose to be more fully hereinafter described.

The shaft 12'projects rearwardly and has mounted thereon a fiber disc 16 keyed to the shaft- 12 so as to rotate therewith and is se cured in place by a nut 17. The disc 16 has formed integrally therewith an arm 18 for a purpose to be more fully hereinafter described. Secured to the disc 16 and adjacent its inner face is a concentrically arranged metal clutch disc or member 19, having a pawl 20 formed thereon by cutting and pressing the clutch plate as clearly illustrated in Fig. 6. This clutch plate 19 is secured to the disc 16 so as to rotate therewith and with the shaft 12.

Loosely mounted upon the shaft 12 is a gear wheel 21 provided with gear teeth 22 on its periphery. This gear wheel has formed thereon a stepped boss 23 carrying a series of ratchet teeth 24. These ratchet teeth lie immediately adjacent the clutch plate 19 and are so arranged as to be engaged by the pawl 20 of the clutch plate 19. Y

Rigidly secured against a shoulder formed by the boss 23 on the gear wheel 27 is a fiber disc 25. This may be secured to the gear wheel by suitablescrews 26 and is provided with a multiplicity of peripheral projections 27. The disc is concentric with the shaft 12 and is securedto the gear wheel 21 so as to rotate therewith.

Meshing with the gear wheel 21 is a spur gear 28 having integrally for'med'therewith an escapement wheel 29, journalled to rotate freely on a screw stud 30screwed into the main plate 10. Disposed adjacent to and engaging with the teeth of the escapement wheel 29 there is provided an escapement dog 31 pivoted to the main disc 10 by a suitable screw stud 32. A spring 33 has one endbe aring upon the dog 31 while its other end is secured to the disc 10 as indicated at 34.

Disposed upon one face of the main plate 10 and between this plate and the finger plate 13 is a dish-shaped plate 35, dished centrally thereof as illustrated clearly in Fig. 2. This dish-shaped plate is provided with a series of radially disposed numerals or other symbols, printed or enamelled thereon and so disposed that the symbols will be visible through the finger openings 15 formed in the finger plate 13. It is obvious that the symbols may be formed on the plate in various ways such, for instance, as paper, celluloid, or other suitable substance provided with the series of symbols.

Disposed between the main plate 10 and the finger plate 13 is a coiled spring 36, one end of which is secured to the main plate 10 and the other end to the finger plate 13. In operation the plate 13 is rotated against the tension of the spring 36, which spring subsequently returns the plate 13 to its normal position. In order to stop the plate 13 in its proper position with'respect to the main plate 10 there is provided a pair 01" cooperating stops 37 and 38 projecting tromthe finger plate 13 and main plate 10 respectively. These stops are so disposed that they lie within the same circumferential path and upon return movement or the plate 13 its corresponding stop 37 will abut the stop 38, thereby preventing further rotation of the plate 13.

Mounted upon the plate 10 there are disposed three spaced spring metal contacts 39, a0 and t1, spaced apart by strips of insulatingmaterial 42 and secured to the plate 10 by screws 43. Spring contact 39 is provided with a projecting arm a l so disposed as to be engaged by the arm 18 formed on the disc 16. The spring contact tO is also provided with an arm l so disposed as to be engaged by the projections 27 on the disc 25. These spring contacts 39, 40 and l1 are connected with the switching apparatus in the telephone central otlice by conductors soldered to lugs 46 projecting from these spring contacts. The mechanisn'i described produces a making and breaking of the circuit into which these spring contacts are interposed which automatically operates magneticdevices in the central ofiice which will set up a number of steps on the switching device at the central office corresponding to the impulses which have been sent out on'the circuit by the contact device.

The exact arrangement of the spring contact will be made more apparent by reference' to Fig. 7. Contact between the members 39 and L0 is established by contact points 47. In normal position of the parts that is, for instance, such as illustrated in Fig. 3, arm 18 ofdisc 16 will engage arm 44;

of contactinember 39 and break contact between this member and the member 40. When, however, the devicehas been set in operation arm 18 is moved from engagement with this contact and connection is made between these two points.

The make break in the circuit occurs between contacts l0 and &1 through contact points l8. This make and break is caused by projections 27 contacting successively witharm 45.

Secured to the main plate and extending up and from the finger plate is a finger stop 49, for the purpose of determining the amount of rotation to be imparted to the finger disc 13. rapertured lugs 50 are also formed on the periphery of the plate 10 to by leased and because of the force exerted by spring 36 the plate is returned to its original position. As the plate 13 was rotated "from its original position the arm 18 was moved out of engagement with the arm of the set of spring contacts. an engagement of the contact points l? thereby partially closing the circuit to the switching apparatus at the central office. Inasmuch as the shaft 12 was rotated likewise in a clockwise direction, the clutch plate 19 was similarly rotated, the pawl 20 sliding over the ratchet teeth 24 formed on the gear wheel 21. 36 begins rotating the finger disc 13 in an anti-clockwise direction the pawl 20 will engage one of the ratchet teeth 24-. and rotate the gear wheel 9,]. in a likewise anti-clockwise direction.

As hereinbe'tore stated the gear wheel meshes with the spur wheel 28, causing spur wheel to rotate and carry with it the escapement wheel 29. The return movement of the finger disc 13 is consequently rctarded. The disc 25 by reason of its connection with the spur wheel 21 is also rotated in an anti-clockwise direction. Dun ing this rotation the projections 27 arranged on the periphery of this disc 25 successively engage the arm 1-5 to depress the same there by intermittently closing contact between the pair of contact points 48. As hereinbefore stated, this causes a making and breaking of the circuit to the switching device the central telephone officeand in the usual manner automatically switching devices.

When the finger disc 13 has been rotated and released as described hereinbetore, the counter clockwise rotation imparted to it and consequently to the-disc 25 causes 8 of the projections 27 to engage the arm. hereby causing a corresponding number of impulses to be sent out over the circuit.

When the finger disc has returned to its normal position the finger is then inserted The subscriber This permits However, as the spring operates magnetic in the aperture which corresponds to the symbol 6 whereby the operation hereinbefore described is repeated. This operation is repeated until the subscribers number to be called has been set up on the device. In Fig. 8 I have illustrated a slighty modified form of retarding mechanism or escapement. Instead of the escapement wheel 29 and dog 31, I provide a governor Wheel 51 which is also formed integrally with the spur wheel 28 as in the structure first described. In this instance, however, there is provided a circular ridge or wall 52 secured to the main disc 10. Radially disposed brake members 53 formed preferably of lead are loosely mounted in the governor wheel and are thrown against the circular wall 52 by centrifugal force thereby imparting to the gear wheel 21 the desired breaking or retarding effect.

The operation of the device is simple and the chances of error are minimized. The various parts of the mechanism are so constrncted that they may in most cases be stamped out of sheet metal, thereby reducing considerable the cost of making the device.

While the structure described and illustrated has proven to be an efficient one, I do not wish to be limited to the details of the same, but reserve the right to make such changes as come within the purview of the claims.

Having thus described my invention, what I claim is:

1. A calling device of the class described comprising a movable dial having a plurality of finger holes for actuating the same, a stationary dial provided with the characters for indicating the positions to which said movable dial can be set, an impulse device mounted concentrically with said movable dial including a fibre disc provided with a plurality of peripheral projections, a clutch plate between said movable dial and said impulse device and fixed to move with said movable dial, a set of contact devices, means cooperating between said contact devices and said impulse Wheel for intermittently operating a pair of said contacts, means rotatable with said clutch plate for controlling another pair of said contacts, means for returning said movable dial to its normal position and a retarding mechanism comprising a dog and ratchet for controlling said rctardin g movement.

2. A calling device of the class described comprising a rotatable dial provided with a series of finger holes for actuating the same, a stationary dial provided with characters for indicating the operating positions to which said movable dial can be set, means disposed between said movable and stationary dials for returning said movable dial to its normal position, a shaft rotatable with said movable dial, an operating arm and clutch plate secured to said shaft and rotatable with said movabe dial, an impulse wheel revolvably mounted on said shaft, said clutch plate coupling said impulse wheel to said shaft for movement in one direction, a set of contact devices, means operated by said impulse wheel for intermittently closing a pair of said contacts and means operated by said arm for controlling another pair of contacts and an escapement mechanism for controlling the return movement of said movable dial. a

3. An arrangement of the class described comprising a main disc, a movable dial, a shaft revolvably supported by said main disc and secured to said movable dial, said movable dial being provided with a series of finger holes for actuating the same, a spring interposed between said main disc and said movable dial for returning said dial to its normal position, a pair of stops projecting from said main disc and said movable dial respectively for limiting the return movement of said movable dial, an impulse device revolvably supported on said shaft, said impulse device comprising a gear wheel and a fiber disc provided with a multiplicity of peripheral projections, an escapement mechanism mounted on said main disc and engaging said gear wheel, a second d s" rigidly secured to said shaft and rotatable therewith, means cooperating with said second disc and said impulse mechanism for clutching said impulse mechanism to said shaft, a set of contact devices and means cooperating between said impulse device and said contact mechanism for intermittently operating a pair of contacts.

HENRY E. ELROD. 

